Demodulation pixels are well known in the field of contactless distance measurement, proximity detection, and multi-dimensional imaging. Demodulation pixels can be employed in time-of-flight techniques. In brief, in some cases, time-of-flight distance measurements, proximity detection and/or multi-dimensional imaging require a modulated light source and at least one demodulation pixel. Modulated light incident on a multi-dimensional object or scene is reflected and captured by a demodulation pixel or demodulation pixel array. The captured light is converted into a signal, wherein amplitude and distance information/data is extracted from the demodulated signal (e.g., the phase shift of the captured light).
Distance measurements, proximity detection, and multi-dimensional imaging data are sometimes combined with spectral data of an object or scene. However, as demodulation pixels are dedicated to the acquisition of distance data they must be combined with separate pixels or a pixel array with corresponding spectral filters in order to acquire both distance data and spectral data with the same optoelectronic device. Accordingly, additional lateral space must be afforded to these separate pixels. In order to reduce the footprint of optoelectronic devices/modules capable of acquiring both distance data and spectral data a challenge exits to combine both of these functions within the same pixel.
Moreover, sensors (e.g. pixels arrays) may have physical defects and limitations. Defects are typical and often due to a defective or impure material, for example. A pixel with a defect may not respond to incident electromagnetic radiation in the same way or to the same degree as a neighboring pixel. For example, a defective pixel may appear saturated regardless of the magnitude of electromagnetic radiation incident on the defective pixel. Further, a pixel may be too dark or too bright by a particular fraction as compared to a neighboring pixel. Consequently, in-situ correction of the defective pixel (at the pixel level) is desirable.
In addition to the physical defects, a pixel's dynamic range is inherently limited. For example, if a pixel is exposed to too much electromagnetic radiation during spectral or distance data acquisition, the pixel may become saturated. Accordingly, the signal from the pixel may not be used; therefore, prevention of saturation (or saturation mitigation) at the sensor-level is also desirable.